Polymerase Chain Reaction (PCR) is a process utilized in biochemical laboratories, to replicate oligonucleotides using polymerase enzymes, such as Taq polymerase. PCR enables rapid replication of oligonucleotides, in particular DNA, so that single copies of an oligonucleotide can be transformed into a significant concentration to enable further manipulation or analysis. The PCR process involves: cycling the temperature of the reaction mixture between two or three temperatures repeatedly to enable replication of the target oligonucleotides. Each cycle can double the number of target oligomer sequences. PCR techniques can amplify a single molecule of an oligonucleotide or oligoribonucleotide about 106 to about 109-fold. A separate assay step can include detecting the amplified oligonucleotides. See U.S. Pat. No. 7,955,840, which is incorporated herein by reference.
The MATCI device disclosed in U.S. Pat. No. 5,589,136 (Northrup, Raymond P. Mariella et al. 1996) is an automated PCR device that uses a modular approach to thermal cycling and analysis. In this patent, which is incorporated herein by reference, each reaction is performed in its own thermal cycling sleeve, and each sleeve has its own associated optical excitation source and fluorescence detector. The low thermal mass of the thermal cycling sleeve allows the MATCI device to realize extremely fast thermal cycling: samples can be heated at a rate of up to 30° C./sec. and cooled at rate as great as 5° C./sec.
Two other commercially available systems, sold under the trade names GENEXPERT (Cepheid, Sunnyvale, Calif.) and RAZOR (Idaho Technology, Inc.), use disposable fluidic cartridges, each containing a flexible reaction chamber that expands under pressure to make tight contact with a solid heater located in the instrument (Petersen, McMillan et al. 1999). RAZOR uses a flexible fluidic pouch and actuators that move a reaction slug within the pouch. The reaction zone walls of the pouch make tight contact with two solid heaters. In both cases, the heater is a solid and the disposable cartridge or pouch contains one or more reaction zones, each with a thin, flexible wall that makes thermal contact with the heater. Another technology, sold commercially under the trade names TRUDIAGNOSIS™ and TRUARRAY™ by Akonni Biosystems (Fredericksburg, Md.), rapidly screens a sample for hundreds of disease markers at one time by using hundreds of molecular biosensors arrayed in a microarray the size of a fingernail. The samples are conveyed through the array using microfluidic channels. The Akonni Biosystems technology can provide accurate diagnostic results in less than 30 minutes to support an informed and timely treatment decision.